Susceptibility to antibiotic combinations of Klebsiella pneumoniae and Acinetobacter baumannii strains isolated from COVID-19 patients

Objective. To assess the susceptibility of K.pneumoniae and A.baumanii strains isolated from hospitalized COVID-19 patients to antibiotics and their combinations.Materials and methods. The minimum inhibitory concentrations (MICs) of meropenem and colistin were determined for 47 A.baumannii and 51K.pneumoniaestrains isolated from the hospitalized COVID-19 patients by the broth microdilution method. The susceptibility to 11 antibiotic combinations was assessed using the method of multiple combination bactericidal testing.Results. Colistin resistance was detected in 31.9 % of A.baumannii strains (MIC50 — 0.5 mg/l, MIC90 — 16 mg/l) and in 80.4 % of K.pneumoniaestrains (MIC50 — 16 mg/l, MIC90 — 256 mg/l). It has been shown that double antibiotic combinations with the inclusion of colistin exhibit bactericidal or bacteriostatic activity against 76.6–87.2 % of A.baumannii strains. Combinations with the addition of meropenem, colistin and macrolides exhibited bactericidal activity against 78.4–80.4 % of K.pneumoniae strains. Combinations of two carbapenems were not active, the combination of meropenem-colistin had a bactericidal effect only in 13.7 % of K.pneumoniae strains.Conclusion. Widespread colistin resistance was found in carbapenem-resistant K.pneumoniae and A.baumannii strains isolated from the hospitalized COVID-19 patients. The combinations of antibiotics that have a synergistic antibacterial effect in their pharmacokinetic/pharmacodynamic concentrations have been determined.

Therapeutic Effects of Inhibitor of ompA Expression against Carbapenem-Resistant Acinetobacter baumannii Strains

The widespread of carbapenem-resistant Acinetobacter baumannii (CRAB) is of great concern in clinical settings worldwide. It is urgent to develop new therapeutic agents against this pathogen. This study aimed to evaluate the therapeutic potentials of compound 62520, which has been previously identified as an inhibitor of the ompA promoter activity of A. baumannii, against CRAB isolates, both in vitro and in vivo. Compound 62520 was found to inhibit the ompA expression and biofilm formation in A. baumannii ATCC 17978 at sub-inhibitory concentrations in a dose-dependent manner. These inhibitory properties were also observed in clinical CRAB isolates belonging to sequence type (ST) 191. Additionally, compound 62520 exhibited a bacteriostatic activity against clinical clonal complex (CC) 208 CRAB isolates, including ST191, and ESKAPE pathogens. This bacteriostatic activity was not different between STs of CRAB isolates. Bacterial clearance was observed in mice infected with bioimaging A. baumannii strain 24 h after treatment with compound 62520. Compound 62520 was shown to significantly increase the survival rates of both immunocompetent and neutropenic mice infected with A. baumannii ATCC 17978. This compound also increased the survival rates of mice infected with clinical CRAB isolate. These results suggest that compound 62520 is a promising scaffold to develop a novel therapeutic agent against CRAB infections.

Antibacterial Effects of New Zealand Plant Extracts against Mycobacteria

<p>Mycobacterium tuberculosis, the causative agent of tuberculosis (TB) has infected approximately 1/3 of the world population, with 9.4 million new TB cases in 2008. In addition to increased cases of drug-resistant strains it is vital that novel antitubercular compounds are discovered in order to treat infections and reduce the time of current TB therapy courses. Natural resources such as plants are now being considered as the focus for discovering new compounds. Plants have long been investigated as a source of antibiotics for the treatment of human disease. New Zealand (NZ) contains a unique and diverse flora; however, to current knowledge no native plants have been examined for antimycobacterial activity. Using ethnobotany as a basis for selection, a total of 58 native plant samples were collected and tested for direct antimycobacterial activity. Samples were extracted with sterile distilled water (SDW), ethanol (EtOH) or methanol (MeOH) and screened for inhibition against the surrogate species, Mycobacterium smegmatis. Active plant samples were then validated for bacteriostatic activity towards M. bovis BCG and M. tuberculosis H37Ra as well as other clinically-important species. Nine extracts from the species Laurelia novae-zelandiae, Lophomyrtus bullata, Metrosideros excelsa, Myoporum laetum, Pittosporum tenuifolium, Pseudopanax crassifolius and Pseudowintera colorata were found to be active against M. smegmatis. Two active extracts were the bark and cambium extracts of Laurelia novae-zelandiae (Pukatea), which were reportedly used by indigenous Māori for the treatment of tubercular lesions. Upon further investigation these extracts also demonstrated bactericidal activity towards M. smegmatis as well as bacteriostatic activity towards the slow-growing species M. bovis BCG and M. tuberculosis. Purification techniques were then performed to improve the efficiency of activity and initial exploration of delivery systems was also examined. The bioactive extracts determined in this research offer a starting point for identifying their chemical basis of antimycobacterial activity with the objective of potentially discovering new anti-tubercular drugs.</p>

Antibacterial Effects of New Zealand Plant Extracts against Mycobacteria

<p>Mycobacterium tuberculosis, the causative agent of tuberculosis (TB) has infected approximately 1/3 of the world population, with 9.4 million new TB cases in 2008. In addition to increased cases of drug-resistant strains it is vital that novel antitubercular compounds are discovered in order to treat infections and reduce the time of current TB therapy courses. Natural resources such as plants are now being considered as the focus for discovering new compounds. Plants have long been investigated as a source of antibiotics for the treatment of human disease. New Zealand (NZ) contains a unique and diverse flora; however, to current knowledge no native plants have been examined for antimycobacterial activity. Using ethnobotany as a basis for selection, a total of 58 native plant samples were collected and tested for direct antimycobacterial activity. Samples were extracted with sterile distilled water (SDW), ethanol (EtOH) or methanol (MeOH) and screened for inhibition against the surrogate species, Mycobacterium smegmatis. Active plant samples were then validated for bacteriostatic activity towards M. bovis BCG and M. tuberculosis H37Ra as well as other clinically-important species. Nine extracts from the species Laurelia novae-zelandiae, Lophomyrtus bullata, Metrosideros excelsa, Myoporum laetum, Pittosporum tenuifolium, Pseudopanax crassifolius and Pseudowintera colorata were found to be active against M. smegmatis. Two active extracts were the bark and cambium extracts of Laurelia novae-zelandiae (Pukatea), which were reportedly used by indigenous Māori for the treatment of tubercular lesions. Upon further investigation these extracts also demonstrated bactericidal activity towards M. smegmatis as well as bacteriostatic activity towards the slow-growing species M. bovis BCG and M. tuberculosis. Purification techniques were then performed to improve the efficiency of activity and initial exploration of delivery systems was also examined. The bioactive extracts determined in this research offer a starting point for identifying their chemical basis of antimycobacterial activity with the objective of potentially discovering new anti-tubercular drugs.</p>

AgNPs Improved Feather Keratin Based Bio-Membrane

AgNPs (Silver Nanoparticles) is successfully prepared and then loaded into feather keratin (FK) based bio-membrane by electrospinning. The morphology, thermal stability, mechanical properties and bacteriostatic activity of the as-prepared AgNPs/FK/PVA bio-membrane are completely developed in this study. Microstructure show that the AgNPs has been dispersed in FK-based bio-membrane without agglomeration. The results suggest that the addition of AgNPs enhanced effectively the performances of FK-based bio-membrane, and the appropriate amount of AgNPs is 1%-2%. The combination of AgNPs and FK can not only ensure the uniform dispersion and antibacterial stability of AgNPs, but also give play to the biocompatibility effect of FK, which makes it natural, safe, stable and degradable, and broaden its application in the field of biomedicine.

Some Indicators of Nonspecific Immunity of Various Breeding Groups of Carp in Different Periods of the Annual Cycle

A comparative study of some parameters of nonspecific immunity in the Angelinskii rubella-resistant variant of the scaly and mirror groups of carp in the prespawning and late feeding periods was carried out. The level of the antimicrobial properties of the C-reactive protein, nonspecific immune complexes in the blood serum, and phagocytic activity of neutrophils were studied. The study showed interbreed and inter-seasonal differences in some indicators. It is concluded that the higher level of bacteriostatic activity of blood serum in the rubella-resistant variant, compared with other groups of carp, provides a low percentage of immunodeficient individuals and resistance to pathogens of infectious diseases.

Heteroaryl-Ethylenes as New Lead Compounds in the Fight against High Priority Bacterial Strains

The widespread use of antibiotics has led to a gradual increase in drug-resistant bacterial infections, which severely weakens the clinical efficacy of antibacterial therapies. In recent decades, stilbenes aroused great interest because of their high bioavailability, as well as their manifold biological activity. Our research efforts are focused on synthetic heteroaromatic stilbene derivatives as they represent a potentially new type of antibiotic with a wide antibacterial spectrum. Herein, a preliminary molecular modeling study and a versatile synthetic scheme allowed us to define eight heteroaromatic stilbene derivatives with potential antimicrobial activity. In order to evaluate our compound’s activity spectrum and antibacterial ability, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests have been performed on Gram-positive and Gram-negative ATCC strains. Compounds PB4, PB5, PB7, and PB8 showed the best values in terms of MIC and were also evaluated for MBC, which was found to be greater than MIC, confirming a bacteriostatic activity. For all compounds, we evaluated toxicity on colon-rectal adenocarcinoma cells tumor cells (CaCo2), once it was established that the whole selected set was more active than 5-Fluorouracil in reducing CaCo-2 cells viability. To the best of our knowledge, the biological assays have shown for these derivatives an excellent bacteriostatic activity, compared to similar molecular structures previously reported, thus paving the way for a new class of antibiotic compounds.

Heteroaryl-Ethylenes as New Lead Compounds in the Fight against High Priority Bacterial Strains

The widespread use of antibiotics has led to a gradual increase in drug-resistant bacterial infections, which severely weakens the clinical efficacy of antibacterial therapies. In recent decades, stilbenes aroused great interest because of their high bioavailability, as well as for their manifold biological activity. Our research efforts are focused on synthetic heteroaromatic stilbene deriva-tives as they represent a potentially new type of antibiotic with a wide antibacterial spectrum. Herein, a preliminary molecular modeling study and a versatile synthetic scheme allowed us to define eight heteroaromatic stilbene derivatives with potential antimicrobial activity. In order to evaluate our compound&rsquo;s activity spectrum and antibacterial ability, Minimum Inhibitory Con-centration (MIC) and Minimum Bactericidal Concentration (MBC) tests have been performed on Gram-positive and Gram-negative ATCC strains. Compounds PB4, PB5, PB7 and PB8 showed the best values in terms of MIC and were also evaluated for MBC, which however was found to be greater than MIC, confirming a bacteriostatic activity. For all compounds, we evaluated toxici-ty on colon-rectal adenocarcinoma cells tumor cells (CaCo2), once established that the whole se-lected set was more active than 5-Fluorouracil in reducing CaCo-2 cells viability. To the best of our knowledge, the biological assays have shown for these derivatives an excellent bacteriostatic activity, compared to similar molecular structures previously reported, thus paving the way for a new class of antibiotic compounds.

PREPARATION OF BACTERICADAL FILLERS FROM GEORGIAN HEULANDITE-CLINOPTILOLITE AND THEIR APPLICATION FOR PAPER PRODUCTION. II. BACTERICADAL PAPER

The purpose of present work was to obtain bactericidal materials using heulandite-clinoptilolite from the Rkoni plot of the Tedzami deposit, Eastern Georgia, and to use them as a filler for the production of bactericidal paper. Materials remaining the zeolite crystal structure, containing over 130 mg/g of silver, 70 mg/g of copper, and 55 mg/g of zinc, and showing bacteriostatic activity towards pathogenic bacteria and fungi were prepared in laboratory and the filled papers were manufactured on the production lines of the GPM company. It was found that the introduction of zeolite fillers leads to an increase in the grammage, thickness and density of the paper, as well as to a certain decrease in the tensile strength in the machine direction. The introduction of zeolite fillers containing divalent metals causes a significant change in surface properties, and samples with a certain copper content become absolutely waterproof. Testing of bacteriostatic activity by disc diffusion method revealed only activity of paper with a silver-containing filler against E. coli and staphylococcus, while the colony forming unit assay indicates the activity of all metal-containing samples against staphylococcus and all zinc-containing samples against E. coli. The greatest activity against E. coli is shown by paper with a high content of zinc, against staphylococcus, paper with a high content of copper. These results are very important from a practical point of view, since they open up the possibility of replacing silver with copper and zinc.